MOSCOW, Feb 22 (Reuters) - Russian Foreign Minister Sergei Lavrov on Saturday expressed his "most serious concern" over what he said was the failure of the Ukrainian opposition to deliver on its Feb. 21 deal with President Viktor Yanukovich.

Yanukovich agreed to sweeping concessions under the peace deal - clinched with the mediation efforts of the foreign ministers of France, Germany and Poland - that include early elections as well as a reduction of presidential powers.

Lavrov spoke on the phone with the European Union trio on Saturday, according to a statement released by the Russian Foreign Ministry, and expressed to them his "most serious concern" about the latest developments in Ukraine.

"The opposition not only has failed to fulfil a single one of its obligations but is already presenting new demands all the time, following the lead of armed extremists and pogromists whose actions pose a direct threat to Ukraine's sovereignty and constitutional order," he told his counterparts.

Lavrov called on Berlin, Warsaw and Paris to exercise their influence with the opposition to ensure a swift fulfilment of the Feb. 21 agreement and the "restraining of rampaging hooligans".

"It's time to stop misleading the international public opinion and pretending that the Maidan represents the interests of the Ukrainian nation," the statement said, referring to the Kiev square that has become the cradle of the protest movement.

The Moscow-backed Yanukovich on Saturday denounced events in Kiev as a coup, as the parliament voted to dismiss him and free his jailed arch-rival Yulia Tymoshenko, while protesters seized his office. (Reporting by Gabriela Baczynska; editing by Andrew Roche)